JPH05208657A - Seat belt retractor - Google Patents

Abstract

PURPOSE:To provide a seat belt retractor with very good stability of a webbing sensor. CONSTITUTION:The center of gravity G of a webbing sensor inertia unit 15, in a condition that it is brought into contact with the first stopper 14h, is set to a position a little apart from a shaft 14f on an extension line in a side of the shaft 14f of a line gamma connecting the center of the first rotary shaft of a reel shaft to the center of the shaft 14f of a lock gear. Thus in the case of drawing out or rewinding webbing at normal time, when the lock gear is rotated, centrifugal force acts on the center of gravity of the inertia unit 15, but since an action line of the force is positioned on the line gamma, moment about the shaft 14f is prevented from acting on the inertia unit 15 by this centrifugal force, to prevent the inertia unit 15 from turning with the shaft 14f serving as the center, and as a result, rotation of the reel shaft is prevented from also stopping by engaging a stopper pawl 15c with a tooth 13c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seat belt device for protecting an occupant mounted on a vehicle such as an automobile,
In particular, the present invention relates to a seat belt retractor that locks the rotation of a reel shaft that winds up a webbing in an emergency to prevent the webbing from extending.

[0002]

2. Description of the Related Art As disclosed in, for example, U.S. Pat. No. 4,796,918 and drawings, a conventional seat belt retractor mounted on a vehicle such as an automobile is a reel for winding webbing. A shaft, a frame that rotatably supports both ends of the reel shaft, and a frame that is disposed between the frame and the reel shaft to allow the reel shaft to rotate during normal operation and operate when necessary to draw out at least the webbing of the reel shaft. Locking means for preventing rotation in a direction, deceleration sensing means for actuating when a deceleration of a vehicle exceeds a predetermined value, and lock actuating means for actuating the locking means by actuation of the deceleration sensing means. Is equipped with.

In such a seat belt retractor, since the reel shaft is normally rotatable freely, the webbing can be pulled out freely and the occupant can freely move forward. Further, in an emergency such as when a large deceleration acts on the vehicle, the deceleration sensing means operates by sensing the deceleration, so that the lock operating means operates the locking means. Since the rotation of the seal shaft is blocked by the operation of this locking means,
Since the extension of the webbing is prevented and the occupant is restrained by the webbing, the forward movement due to the inertia of the occupant is prevented.

By the way, in the conventional general seat belt retractor, the lock operating means normally rotates together with the reel shaft, and the deceleration detecting means operates to cause relative rotation with the reel shaft. And a webbing withdrawal speed sensing means (webbing sensor) that is activated when the webbing is withdrawn at a withdrawal speed higher than a predetermined value. Means pivotable to the locking means actuating member between a non-actuating position in which the locking means actuating member is free to pivot and an operating position in which the locking means actuating member is prevented from pivoting at least in the webbing withdrawal direction Often have an inertial body provided in.

According to this retractor, when the webbing is suddenly pulled out at a withdrawing speed higher than a predetermined value, the webbing withdrawing speed sensing means senses it and prevents the rotation of the locking means actuating member to prevent the rotation of the reel shaft. By causing a relative rotation between them, the lock means is operated to prevent the reel shaft from rotating, and the withdrawal of the webbing is prevented.

[0006]

However, in such a seat belt retractor, since the inertia member is rotatably attached to the locking means operating member, when the locking means operating member is normally rotated when the webbing is pulled out. ,
The inertial body also revolves around the rotation axis of the lock operating member. Due to the revolution of the inertial body, a centrifugal force acts on the inertial body, so that the inertial body may oscillate around its rotation axis and prevent the locking means operating member from rotating. As described above, the conventional seat belt retractor does not always have sufficient stability of the webbing sensor.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a seat belt retractor in which the stability of the webbing sensor is extremely good.

[0008]

In order to solve the above-mentioned problems, the invention of claim 1 relates to a reel shaft for winding webbing, a frame for rotatably supporting both ends of the reel shaft, and the frame. And a locking means which is arranged between the reel shafts to allow the rotation of the reel shaft during normal operation and to operate when necessary to prevent the rotation of the reel shaft in at least the webbing withdrawing direction, and a deceleration of a predetermined value or more on the vehicle. Deceleration sensing means activated when applied,
Lock actuating means for actuating the lock means by actuating the deceleration sensing means, and the lock actuating means further comprises:
A locking means operating member that normally rotates together with the reel shaft and operates the locking means by relative rotation with the reel shaft due to the operation of the deceleration sensing means, and a webbing at a withdrawing speed of a predetermined value or more. And a webbing withdrawal speed detecting means that is activated when the webbing withdrawal speed is detected, the webbing withdrawing speed detecting means includes a non-operating position for allowing the locking means operating member to freely rotate the locking means operating member, and In a seat belt retractor having an inertial body rotatably provided at least between an operating position that prevents the locking means operating member from rotating in the webbing pull-out direction, the inertial body is
When the inertial body is in the non-operating position, the center of gravity of the inertial body is set to be on the extension line of the inertial body on the rotation axis side of the straight line connecting the rotation axis of the inertial body and the rotation axis of the locking means operating member. Is characterized by.

Further, according to a second aspect of the present invention, when the inertial body is in the operating position, a locking claw that engages with an engaged portion provided on the frame is provided integrally with the inertial body. It is characterized by being.

[0010]

In the seat belt retractor according to the first aspect of the present invention having such a structure, when the locking means operating member is rotated during the normal webbing withdrawal or winding, centrifugal force is exerted on the center of gravity of the inertial body. The action line is located on the extension line of the straight line connecting the rotation axis of the inertial body and the rotation axis of the locking means actuating member, so that the centrifugal force causes a moment around the rotation axis to act on the inertial body. There is no such thing. Therefore, the inertial body does not rotate carelessly about its axis of rotation. This improves the stability of the webbing sensor.

Further, according to the second aspect of the present invention, since the locking claw is formed integrally with the inertial body, the machine is more mechanical than the conventional general retractor in which the locking claw and the inertial body are formed separately. Friction is small, and the stability of the webbing sensor is good. Especially in this case, since the inertial body does not rotate carelessly when the locking means operating member normally rotates, the locking claw may engage with the engaged portion of the frame to stop the rotation of the reel shaft. Absent. This further improves the stability of the webbing sensor.

[0012]

1 to 3 are exploded perspective views showing an embodiment of a seat belt retractor according to the present invention, FIG. 1 is a central portion thereof, FIG. 2 is a left portion thereof, and FIG. It is the right part. Then, the lines A ₁ , B ₁ and C in FIG.
₁ and D ₁ and the lines A ₂ , B ₂ , C ₂ and D _{2 of} FIG. 2 are aligned,
Lines E ₁ , F ₁ , C ₁ , G ₁ , H ₁ of FIG. ₁ and lines E ₃ , F ₃ , C ₃ ,
By matching G ₃ and H ₃ with each other, an exploded perspective view of the whole of this embodiment is constructed. 4 to 6 show a state in which the seat belt retractor of this embodiment is assembled, FIG. 4 is a right side view of the seat belt retractor with a cover removed, and FIG. 5 is a V in FIG.
6 is a sectional view taken along the line V, and FIG. 6 is a partial left side view partially showing a state in which the biasing force applying means 5 is removed from FIG.

As shown in FIGS. 1 to 6, the seat belt retractor 1 in this embodiment has a right side wall 2a, a left side wall 2a, and a right side wall 2a.
It is provided with a frame 2 formed in a U shape having 2b. The right and left side walls 2a and 2b are connected to each other by a connecting member 2c, and the frame 2 is reinforced by this. Further, as shown in FIG. 7, a circular hole 2d is formed in the right side wall 2a, and a circular hole 2e is formed in the left side wall 2b as shown in FIG.
Furthermore, the inner peripheral surfaces of the holes 2d and 2e in the right and left side walls 2a and 2b respectively have a predetermined number of tooth-shaped teeth 2 over the entire circumference.
f ..., 2g ... are formed. These teeth 2f, 2g are formed in the same shape as a triangular chevron, in which case the surface facing the webbing pull-out direction α is a relatively steep slope, whereas the webbing take-up direction is The surface facing β is a relatively gentle slope. And
The phase of the tooth 2g on the left side is set to advance from the phase of the tooth 2f on the right side in the webbing drawing-out direction α by a predetermined angle (for example, 3 °).

Further, the left side wall 2b has three locking holes 2
A guide hole 2q consisting of h, 2i, 2j and a long hole is formed, and four locking holes 2 are formed in the right side wall 2a.
A guide hole 2p formed by k, 2m, 2n, 2r and a long hole is formed. Further, a locking projection 2s is provided on the upper end of the right side wall 2a so as to project upward.

As shown in FIG. 5, a reel shaft 4 for winding the webbing 3 is disposed between the left and right side walls 2a and 2b of the frame 2. As shown in FIG. 9, the reel shaft 4 includes a central webbing take-up portion 4a and a circular flange-shaped portion 4b formed at the right and left ends of the webbing take-up portion 4a to guide the take-up of the webbing 3. ，
4c, a first rotating shaft 4d provided in the central portion of the flange-shaped portion 4b and protruding outward in the axial direction, and a second rotating shaft provided in the central portion of the flange-shaped portion 4c and coaxial with the first rotating shaft 4d. It is composed of a shaft 4e. The webbing take-up portion 4a has a radial through hole 4f into which the tip of the webbing 3 is inserted and locked so that the webbing 3 can be taken up.
Has been drilled. One end portion side of the through hole 4f is formed wide, so that the through hole 4f is formed as a stepped hole having a step portion 4g, and the tip of the webbing 3 is locked to the step portion 4g. ing.

As shown in FIG. 10, the right flange portion 4
The first concave fitting portion 4h in which the pawl spring 18 (shown in FIG. 1) is housed and the second concave fitting portion in which the claw portion 17c of the main pawl 17 (details are shown in FIG. 20 described later) are arranged in b. A portion 4i, a load receiving portion 4k having a load receiving surface 4j for receiving a load applied to the claw portion 17c of the main pawl 17, and an axial through hole 4m into which the joint pin 19 is rotatably fitted. The through hole 4m formed at the end of the through hole 4m and the concentric circular third concave fitting portion 4n are provided. The first, second and third concave fitting portions 4h, 4i, 4n are recessed in the axial direction most deeply with respect to the surface of the outer peripheral edge portion 4p of the flange-shaped portion 4b, and the surface of the load receiving portion 4k is flange-shaped. The surface of the outer peripheral edge portion 4p of the portion 4b is shallower than the concave fitting portions 4h, 4i, 4n and is recessed in the axial direction. Therefore, between the second concave fitting portion 4i and the first concave fitting portion 4h forming portion of the outer peripheral edge portion 4p of the flange portion 4b, the flange portion 4b.
Between the outer peripheral edge portion 4p and the load receiving portion 4k and between the second concave fitting portion 4i and the load receiving portion 4k.
q, 4r, and 4s are formed. Also, the load receiving surface 4j
Is formed of an arc of a predetermined length concentric with the through hole 4m.

Further, when the reel shaft 4 is disposed between the right and left side walls 2a and 2b on the outer peripheral surface of the flange portion 4b, the reel shaft 4 is axially guided with respect to the right side wall 2a. The right side guide portions 4t are formed at three locations at equal intervals in the circumferential direction. These right guide parts 4t are on the right,
The size is set so that it cannot easily pass through the holes 2d and 2e of the left sidewalls 2a and 2b. However, these right side guide portions 4t have a predetermined number of teeth 4t ₁ , and these teeth 4t ₁ are formed to be similar to the teeth 2f and 2g formed on the left and right side walls 2a and 2b and slightly smaller. There is. Therefore, when the tooth 4t ₁ is aligned with the tooth 2f or the tooth 2g, the flange-shaped portion 4 having the right guide portion 4t is formed.
b can pass through the holes 2d and 2e.

Further, the tip of the first rotating shaft 4d has a small diameter portion 4d.
₁ are, the smaller-diameter portion 4d ₁ is rotatably fitted supported on the small hole 13n of the lock gear first cover 13 as described below.

Further, as shown in FIG. 11, the left flange portion 4c has a fourth concave fitting portion 4 in which a claw portion 20c of a backup pawl 20 (details are shown in FIG. 22, which will be described later) is arranged.
u, a load receiving portion 4w having a load receiving surface 4v for receiving a load applied to the claw portion 20c of the backup pawl 20, an axial through hole 4m into which the joint pin 19 is rotatably loosely fitted, A fifth concave fitting portion 4x, which is concentric with the through hole 4m and is formed at the end of the through hole 4m, is provided. The fourth and fifth concave fitting portions 4u, 4x are recessed in the axial direction most deeply with respect to the surface of the outer peripheral edge portion 4y of the flange-shaped portion 4c, and the surface of the load receiving portion 4w is the outer peripheral edge of the flange-shaped portion 4c. The concave fitting portions 4u, 4 with respect to the surface of the portion 4y
It is shallower than x and dented in the axial direction. Therefore, the fourth
Between the concave fitting portion 4u and the outer peripheral edge portion 4y of the flange-shaped portion 4c,
Step portions 4z, 4A, 4B are formed between the outer peripheral edge portion 4y of the flange-shaped portion 4c and the load receiving portion 4w, and between the fourth concave fitting portion 4u and the load receiving portion 4w. Further, the load receiving surface 4v is formed of an arc of a predetermined length which is concentric with the through hole 4m.

Further, when the reel shaft 4 is disposed also on the outer peripheral surface of the flange-shaped portion 4c between the right and left side walls 2a and 2b, the reel shaft 4 is axially guided with respect to the left side wall 2b. The left side guide portions 4D are formed at three locations in the circumferential direction at equal intervals. These left guide portions 4D are on the right,
The size is set so that it cannot easily pass through the holes 2d and 2e of the left sidewalls 2a and 2b. However, these left guide portions 4D have a predetermined number of teeth 4D ₁ , and these teeth 4D ₁ are formed to be similar to the teeth 2f and 2g formed on the left and right side walls 2a and 2b and slightly smaller. There is. Therefore, when the tooth 4D ₁ is aligned with the tooth 2f or the tooth 2g, the flange-like portion 4 having the left guide portion 4t is formed.
c can pass through the holes 2d and 2e.

Further, in the second rotary shaft 4e projecting in the axial direction from the flange portion 4c, the tip portion 4e ₁ is formed in a circular cross section, and the root portion 4e ₂ is a square cross section (in the case of this embodiment, a square shape). ) Is formed.

As is apparent from FIG. 9, the through hole 4m not only penetrates the flange portions 4b and 4c, but also penetrates the central webbing winding portion 4a in the axial direction, that is, the through hole 4m is It is provided so as to penetrate the reel shaft 4 in the axial direction.

As shown in FIGS. 2 and 5, the left side wall 2b
A biasing force applying means 5 for applying a winding force of the webbing 3 to the reel shaft 4 is attached to the. Furthermore,
As shown in FIGS. 1, 3 and 5, the seat belt lock operating means 6 is attached to the right side wall 2a, and when a predetermined deceleration acts on the vehicle as shown in FIGS. 3 and 5, A deceleration sensing means (vehicle sensor) 7 for sensing the deceleration and operating the seat belt lock operating means 6 is provided.

The urging force applying means 5 is a power spring 8 composed of a spiral spring, and an inner end 8 of the power spring 8.
A bush 9 to which a is connected to apply a spring force, an outer end 8b of the power spring 8 is fixed, and a spring case 10 that houses the power spring 8 and a cover 11 that is attached to the spring case 10 and covers the power spring 8 are provided. It consists of and.

As shown in FIG. 12, at the center of the bush 9, the root portion 4e of the second rotating shaft 4e of the reel shaft 4 is provided.
A through hole 9a into which ₂ can be fitted is bored in the axial direction.
The cross-sectional shape of the through hole 9a is the root portion 4 of the second rotating shaft 4e.
It is a prism having the same shape as the cross-sectional shape of e ₂ . Further, the bush 9 is provided with four grooves 9b, 9c, 9d, 9e having a U-shaped cross section, which are open to the outer peripheral surface thereof. Among these grooves, the groove 9b and the groove 9d, and the groove 9c and the groove 9e are respectively arranged on the radially opposite sides with respect to the center of the bush 9. As will be described later, spring pins 12 (shown in FIG. 2) are inserted into these grooves. Further, the bush 9 is provided with a locking groove 9f into which the inner end 8a of the spring 8 is fitted and locked.

The bush 9 is adapted to be relatively non-rotatably fitted and connected to the second rotary shaft 4e by fitting the root portion 4e ₂ of the second rotary shaft 4e into the hole 9a. The spring force of the spring 8 causes the winding direction β of the webbing 3 on the reel shaft 4 via the bush 9.
Is always active.

As shown in FIG. 13, the spring case 1
0 is provided with a hole 10a into which the root portion 4e ₂ of the second rotation shaft 4e of the reel shaft 4 is loosely fitted, and a pair of small holes 10 through which the spring pin 12 passes.
b and 10c are provided so as to sandwich the hole 10a. Also,
A locking portion 10d for locking the outer end 8b of the spring 8 is provided near the outer peripheral end of the spring case 10.

As shown in FIG. 14, the cover 11 has a tip portion 4e of the second rotating shaft 4e of the reel shaft 4 at the substantially central portion.
A hole 11a for rotatably supporting ₁ is formed and a pair of small holes 11 through which the spring pin 12 penetrates.
b and 11c are provided so as to sandwich the hole 11a. Also,
The flange portion formed on the end portion of the cover 11 is provided with three locking protrusions 11d, 11e, 11f. These locking protrusions 11d, 11e, 11f are respectively corresponding locking holes 2h, 2d formed in the left side wall 2b of the frame 2.
It is adapted to be fitted and locked to i and 2j, whereby the biasing force applying means 5 is detachably attached to the left side wall 2b of the frame 2.

By the way, when assembling the seat belt retractor, the urging force applying means 5 is preassembled as a sub-assembly, and the sub-assembly is assembled into the frame 2.
It is attached to the left side wall 2b. In that case,
When the urging force applying means 5 is sub-assembled, a spring force is constantly applied to the reel shaft 4 in the webbing winding direction β.
In order to apply the power spring 8 to the webbing, it is necessary to keep the power spring 8 wound in the webbing pull-out direction α by a predetermined amount. Therefore, the spring pin 12 as shown in FIG. 2 is used.

As shown in detail in FIG. 15, the spring pin 12 is formed by bending an elastic wire.
The book includes rotation preventing arms 12a and 12b. And
In order to prevent the power spring 8 from being rewound in the sub-assembly state of the urging force applying means 5, these rotation preventing arms 12a and 12b are provided with small holes 11b and 11c of the spring cover 11 as shown in FIG. By penetrating one of the grooves 9b and 9c of the bush 9 and one of the grooves 9d and 9e into the small holes 10b and 10c of the spring case 10, the power spring 8 is prevented from rewinding. On the other hand, the seat belt lock operating means 6 is a lock gear first cover 13 fixed to the right side wall 2a of the frame 2, a lock gear 14, and a swingable attachment to the lock gear 14, and a webbing withdrawing speed sensing means (webbing sensor). Inertial body 15
A control spring 16 disposed between the lock gear 14 and the inertial body 15, one end rotatably supported by the third recessed fitting portion 4n formed on the flange-shaped portion 4b of the reel shaft 4, and the other end. The main pawl 17 serving as a locking portion arranged in the second recessed fitting portion 4i and the first recessed fitting portion 4h of the reel shaft 4 are housed and contracted between the reel shaft 4 and the main pawl 17. Paul spring 18
A joint pin 19 penetrating through the axial hole 4m of the reel shaft 4; and a fifth concave fitting portion 4x connected to one end of the joint pin 19 and having one end formed in the flange-shaped portion 4c of the reel shaft 4. The backup gear 20, which is movably supported and has the other end serving as a locking portion arranged in the fourth recessed fitting portion 4u, and the lock gear first cover 13, which is fitted and supported by the right side wall 2a of the frame 2. Lock gear 1
4, inertia body 15, main pawl 17, joint pin 1
9 and a lock gear second cover 21 that covers the deceleration sensing means 7. Further, the seat belt retractor 1 includes a webbing guide 2 that guides the webbing 3.
Equipped with 2.

As shown in FIGS. 16 and 17, the lock gear first cover 13 has a relatively large through hole 13a, and the inner peripheral surface of the through hole 13a has a predetermined number of teeth 13c, all over the circumference. 13c, ... Are formed. These annular teeth 13c are formed in a triangular chevron,
In that case, the surface facing the webbing pull-out direction α is substantially vertical, whereas the webbing take-up direction β
The surface facing is a relatively gentle slope. Further, as shown in FIG. 16, the lock gear first cover 13
Three locking projections 13d, 13e, 13f are provided on the surface of the frame 2 facing the right side wall 2a. The lock gear first cover 13 is detachably attached to the frame 2 by fitting the locking protrusions 13d, 13e, 13f into the locking holes 2k, 2m, 2n formed in the right side wall 2a.

Further, as shown in FIG. 17, the lock gear first
An accommodating portion 13g of the deceleration sensing means 7 is provided so as to open on the surface of the cover 13 opposite to the surface on the locking projections 13d, 13e, 13f side. A pair of guide members 13 for guiding and fixedly supporting the deceleration detecting means 7 in the direction perpendicular to the paper surface of FIG.
h, 13i are provided. These guide members 13
On the surfaces of h and 13i facing each other, concave fitting portions 13j and 13k having trapezoidal cross-sections extending in the longitudinal direction of the guide members 13h and 13i are formed, respectively. That is, the concave fitting portion 1
Both side walls 13j ₁ , 13j ₂ , 13k ₁ , 13k _{2 of} 3j, 13k
Are inclined surfaces.

Further, a substantially cruciform side wall 13m is formed on the surface of the lock gear first cover 13 opposite to the surface on the side of the locking projection, and in this case, the intersection of the side walls 13m has an annular tooth 13c. It is located almost in the center. A small hole 13n is formed at the center of the annular tooth 13c at the intersection of the side walls 13m. The first rotation shaft 4d of the reel shaft 13 is provided in the small hole 13n.
The tip small diameter portion 4d ₁ is loosely fitted with almost no gap, whereby the first rotating shaft 4d is fitted into the small hole 13n.
Rotatably supported by.

As shown in FIG. 18A, the lock gear 14 is composed of a circular flat plate portion 14a and an annular flange 14b formed at the outer peripheral end of the flat plate portion 14a. The outer peripheral surface of the flange 14b has a predetermined number of teeth 14c, 1
4c, ... Are formed. These teeth 14c are formed in a triangular chevron, and in this case, the surface facing the webbing pull-out direction α is a relatively gentle inclined surface, whereas the surface facing the webbing winding direction β is a surface. Is almost vertical.

As shown in FIGS. 7A and 7B, the left side surface (flange 14) of the flat plate portion 14a in FIG.
A spring receiving member 14d that supports one end of the control spring 16 is erected on the surface surrounded by b). The spring receiving member 14d has a spring guide portion 14e.
Are erected parallel to the flat plate portion 14a. Flat plate part 1
A shaft 14f is erected on the shaft 4a, and an inertia body 15 is rotatably supported on the shaft 14f as described later. An arc-shaped retaining member 14g is provided upright adjacent to the shaft 14f.

As shown in FIG. 3C, a locking claw 14g ₁ is formed at the tip of the retaining member 14g.
The locking claw 14g ₁ has an inclined upper surface and is formed so as to slightly project toward the shaft 14f. Therefore, the inertial body 15 is
Since the inertial member 15 presses the inclined surface of the locking claw 14g ₁ when it is fitted to, the retaining member 14g elastically deforms so as to slightly open the gap between the shaft 14f and the retaining member 14g, As a result, the inertial body 15 gets over the locking claw 14g ₁ and is housed in the space surrounded by the shaft 14f and the retaining member 14g. In this state, the inertial body 1
Even if 5 moves in the axial direction upward in FIG. 18 (c), the locking claw 14g1 prevents the movement of the shaft ₅ in the axial direction, so that it is prevented from coming off the shaft 14f.
However, the amount of protrusion of the locking claw 14g ₁ is small, and the inertial body 1
5 and the locking claw 14g ₁ are lightly engaged,
By applying a slight external force to the inertial body in the direction of coming out of the shaft 14f, the inertial body 15 can easily get out of the shaft 14f by overcoming the locking claw 14g ₁ . With this retaining member 14g, the inertial body 15
The attachment / detachment to / from the shaft 14f is facilitated, and the inertial body 15 is reliably supported by the shaft 14 so as to be swingable.

Further, the flat plate portion 14a is provided with a first stopper 14
The h and the second stopper 14i are provided upright, and a cylindrical rotating shaft 14j is provided upright in the axial direction at the center of the flat plate portion 14a. The first rotating shaft 4d of the reel shaft 4 penetrates through the hole of the cylindrical rotating shaft 14j, and the rotating shaft 14j is rotatable about the first rotating shaft 4d.

Further, the flat plate portion 14a includes the flat plate portion 14a.
First, second and third cam holes 14 of a predetermined shape penetrating the
k, 14m, and 14n are provided respectively. As shown in FIG. 3B, the peripheral portions of the first, second, and third cam holes 14k, 14m, 14n ensure that the cam followers fitted in these cam holes are guided. Moreover, in order to reinforce the peripheral portion of the cam hole, the flat plate portion 14a
Is formed thicker than. The first cam hole 14k is formed as an arc centered on the rotation shaft 14j.

On the other hand, a spring receiving member 14p for supporting one end of the pawl spring 18 is erected on the right side surface (the surface not surrounded by the flange 14b) of the flat plate portion 14a in FIG. A spring guide portion 14q is erected on the spring receiving member 14p in parallel with the flat plate portion 14a.

As shown in FIG. 19, the inertial body 15 is formed from a flat plate into a substantially C shape, and a boss portion 15b having a hole 15a is formed in the center thereof. Further, a locking claw 15c is integrally formed at one end, and
A spring receiving portion 15d and a spring guide portion 15e, which support and guide the other end of the control spring 16, are provided at the other end. As shown in FIG. 4, the inertia body 15 is supported by the lock gear 14 rotatably around the shaft 14f by fitting the hole 15a into the shaft 14f of the lock gear 14. In that case, as described above, the boss portion 15b of the inertial body 15 is locked to the locking claw 14g ₁ of the retaining member 14g, so that the shaft 1 of the inertial body 15 is locked.
It is prevented from coming off from 4f. Further, since the locking claw 15c is formed integrally with the inertial body 15, the locking claw 15c is formed.
The mechanical friction is smaller than that of the conventional general retractor in which the inertial member 15 and the inertial member 15 are formed separately, and the stability of the webbing sensor is improved.

As shown in FIG. 4, the control spring 16
Is a state in which the inertia body 15 is swingably supported by the shaft 14f, and both the guide portions 14 of the lock gear 14 and the inertia body 15 are
It is fitted in e and 15e, and is contracted between the spring receiving member 14d and the spring receiving portion 15d. Therefore, the inertial body 15 is constantly urged in the α direction with respect to the lock gear 14 by the spring force of the control spring 16, and is normally held at the position in contact with the first stopper 14h as shown by the solid line. It In addition, the inertial body 15 is the lock gear 14
When rotating in the β direction against the spring force of the control spring 15, the second stopper 14 as shown by the chain double-dashed line
It is a position in contact with i.

By the way, as shown by the solid line in FIG. 4, the center of gravity G of the inertial body 15 has the first rotation shaft 4 of the reel shaft 4 in a state where the inertial body 15 is in contact with the first stopper 14h.
The line γ connecting the center of d and the center of the shaft 14f of the lock gear 14 is set at a position slightly separated from the shaft 14f on an extension line on the shaft 14f side. As a result, when the lock gear 14 rotates when the webbing 3 is normally pulled out or wound up, the centrifugal force F acts on the center of gravity of the inertial body 15.
Since the line of action of the centrifugal force F is located on the line γ, the moment F about the axis 14f does not act on the inertial body 15 by the centrifugal force F.

Therefore, when the reel shaft 4 normally rotates, the inertial body 15 does not rotate about the shaft 14f, and as a result, the locking claw 15c is inadvertently toothed on the lock gear first cover 13. Also, the rotation of the reel shaft 4 is not stopped by engaging with 13c.

As shown in FIGS. 4 and 5, when the seat belt retractor 1 is assembled, the lock gear first
The teeth 13c of the cover 13 are located inside the annular flange 14b of the lock gear 14 and between the flange 14b and the inertia body 15. Then, when the inertial body 15 is in the normal state, as shown in FIG.
Since it is held at the position where it abuts on the first stopper 14h shown by the solid line, the locking claw 15c is held at the non-engaging position apart from the tooth 13c. Further, when the inertial body 15 is in the position where it is in contact with the second stopper 14i shown by the chain double-dashed line in FIG. 4, the locking claw 15c is in the position where it can engage with the tooth 13c.

When the lock claw 15c is in the engageable position and the lock gear 14 rotates in the webbing drawing-out direction α, the lock claw 15c engages with the tooth 13c, and the lock gear 14c.
Is further prevented from rotating in the webbing pull-out direction α. When the lock gear 14 rotates in the webbing winding direction β when the locking claw 15c is in the engageable position, the locking claw 1
The lock gear 14 is rotatable with respect to the webbing winding direction β because 5c moves along the gentle inclined surface of the tooth 13c against the control spring 16 and jumps over the tooth 13c.

As shown in FIG. 20, the main pawl 17 is formed into a substantially fan shape, and the through hole 17a is formed in the key portion of the fan.
A boss portion 17b having a is formed. A claw portion 17c is formed at an end portion on the side opposite to the key of the fan, and a tooth 17d engageable with a tooth 2f of the right side wall 2a of the frame 2 is formed at a tip end of the claw portion 17c. There is. And
As shown in FIG. 10 (a), the boss portion 17 b is rotatably fitted in the third recessed fitting portion 4 n of the flange-shaped portion 4 b of the reel shaft 4. The reel shaft 4 is swingably provided around the portion 17b. In that case,
The main pawl 17 abuts on the step portion 4q formed on the flange-shaped portion 4b, thereby preventing further rotation in the α direction and abutting on the step portion 4r formed on the flange-shaped portion 4b. As a result, further rotation in the β direction is prevented. That is, these step portions 4q and 4r serve as stoppers for restricting the rotation of the main pawl 17 in the α direction.

When the main pawl 17 is in contact with the stepped portion 4q, the teeth 17d at the tip end of the main pawl 17 have the flange-shaped portion 4a.
In the state of being completely inward from the outer peripheral surface of b and in contact with the step portion 4q, the teeth 17d project outward from the outer peripheral surface of the flange-like portion 4b, and the right wall 2 of the frame 2 as described later.
The position is such that it is engaged with the tooth 2f of a. A load transmission portion 17e is formed at the end of the claw portion 17c opposite to the tooth 17d. The load transmitting portion 17e is formed by an arc formed of a circle concentric with the through hole 17a and the boss portion 17b.

As shown by the chain double-dashed line in FIG. 10A, the main pawl 17 has a boss portion 17b rotatably fitted in the third recessed fitting portion 4n of the reel shaft 4 so that the main pawl 17 has a right side. It is attached to the flange portion 4b. When the main pawl 17 is attached to the right flange portion 4b, the claw portion 17c is located in the second concave fitting portion 4i, and the load transmitting portion 17e comes into contact with the load receiving surface 4j of the reel shaft 4. .. In that case, the load transmission part 17
e and the load receiving surface 4j of the reel shaft 4 are both formed by the arcs of the same concentric circles, the load transmitting portion 17e does not contact the load receiving surface 4j of the reel shaft 4 regardless of the position of the main pawl 17. Always abut.

When the load transmitting portion 17e contacts the load receiving surface 4j of the reel shaft 4 in this way, the load w applied to the claw portion 17c of the main pawl 17 is transmitted as shown in FIG. Load receiving surface 4 from the portion 17e
It is transmitted to j and is supported by the reel shaft 4. In such a load supporting structure, since the tooth 17d, which is a load point, and the load transmitting portion 17e are relatively close to each other, the main pawl 17 is hardly bent, and only the compression is applied. Become. Moreover, since the load transmitting portion 17e and the load receiving surface 4j are in surface contact with each other,
The load is transmitted to the reel shaft 4 in a wide area, and the stress generated by the dispersed load is relatively small. Therefore, the strength of the main pawl 17 may be smaller than that of the conventional main pawl.
Can be made of a relatively light material such as resin.

Further, the load transmitting portion 17 of the main pawl 17
A cylindrical cam follower 17f is provided on the surface opposite to the e side, and the cam follower 17f is provided in the lock gear 14a.
Of the third cam hole 14n.
You will be guided along 4n.

The pawl spring 18 is housed in the first recessed fitting portion 4h of the reel shaft 4 and the lock gear 1
4 is fitted in the spring guide portion 14q, and is contracted between the wall surface of the first concave fitting portion 4h and the spring receiving portion 14p. Therefore, the pawl spring 18 is
7 with respect to the reel shaft 4 in the webbing pull-out direction α
Always urged. Therefore, by the biasing force of the pawl spring 18, the main pawl 17 is normally in contact with the step portion 4q formed on the flange-shaped portion 4b.

As shown in FIG. 21, the joint pin 19
The main body 19a has a circular cross section, and an arm 19b extending at a right angle to the main body 19a is formed at the right end of the main body 19a in FIG. This arm 1
A cam follower 19c having a circular cross section is provided at the tip of 9b. This cam follower 19c has a lock gear 14
The second cam hole 1 is fitted into the second cam hole 14m of
It is supposed to be guided to 4m. A shaft portion 19d having a rectangular cross section is formed on the other end of the main body 19a.
The shaft portion 19d is fitted into a hole formed at one end of a backup pawl 20 described later such that it cannot rotate relatively. Therefore, when the cam follower 19c is guided by the second cam hole 14m and the arm 19b rotates, the main body 1
9a rotates, the rotation of the main body 19a is transmitted to the backup pawl 20, and the backup pawl 20 moves to the second position.
The cam follower 19c guided by the cam hole 14m is rotated according to the movement of the cam follower 19c.

As shown in FIG. 22, the backup pawl 20 is formed in a substantially fan shape, and a boss portion 20b having a through hole 20a having a rectangular cross section is formed at a key portion of the fan. A claw portion 20c is formed at the end of the fan opposite to the key, and a tooth 20d engageable with the tooth 2g of the left side wall 2b of the frame 2 is formed at the tip of the claw portion 20c. There is. Then, as shown in FIG. 11A, the boss portion 2
0b is rotatably fitted to the fifth recessed fitting portion 4x of the flange-shaped portion 4c of the reel shaft 4, so that the backup pawl 20 is mounted on the reel shaft 4 about the boss portion 20b. It is designed to be swingable. In that case, the backup pawl 20 has an outer peripheral edge portion 4y of the step portion 4z formed in the flange-shaped portion 4c.
By contacting the portion 4z ′ located at the end, further rotation in the α direction is prevented, and by contacting the stepped portion 4A formed on the flange-shaped portion 4b, further rotation in the β direction is prevented. Rotation is blocked. That is, these step portions 4z ', 4A serve as stoppers for restricting the rotation of the main pawl 7 in the α direction. Further, the backup pawl 20 has the teeth 20d at the tip thereof in contact with the step portion 4z 'and the flange-like portion 4a.
In the state of being completely inward from the outer peripheral surface of c and in contact with the step portion 4A, the teeth 20d project outward from the outer peripheral surface of the flange-shaped portion 4c, and the left side wall 2 of the frame 2 will be described later.
The position is such that the tooth 2g of b is engaged. A load transmission portion 20e is formed at the end of the claw portion 20c opposite to the tooth 20d. The load transmission portion 20e is formed by an arc formed of a circle concentric with the through hole 20a and the boss portion 20b.

As shown in FIG. 11A, when the backup pawl 20 is attached to the left flange portion 4c, the claw portion 20c is located in the fourth concave fitting portion 4u and the load transmitting portion 20e is in the reel. It comes into contact with the load receiving surface 4v of the shaft 4. In that case, the load transmission unit 20
For e, the load transmitting portion 20e always contacts the load receiving surface 4v of the reel shaft 4 regardless of the position of the backup pawl 20.

As the load transmitting portion 20e contacts the load receiving surface 4v of the reel shaft 4 in this way, the load w'applied to the claw portion 20c of the backup pawl 20.
However, as shown in FIG. 3B, the load is transmitted from the load transmitting portion 20e to the load receiving surface 4v and supported by the reel shaft 4. Similar to the main pawl 17 mentioned above,
In such a load supporting structure, the tooth 2 which is the load point
Since 0d and the load transmission unit 20e are relatively close to each other,
Bending hardly acts on the backup pawl 20, and almost only compression acts on it. Moreover, since the load transmitting portion 20e and the load receiving surface 20j are in surface contact with each other,
The load is transmitted to the reel shaft 4 in a wide area, and the stress generated by the dispersed load is relatively small. Therefore, the strength of the backup pawl 20 may be smaller than that of the conventional backup pawl, and the backup pawl 17 can be formed of a relatively light material such as resin.

As shown in FIG. 23, the lock gear second cover 21 includes a flat plate portion 21a, a flange portion 21b formed on the outer peripheral edge of the flat plate portion 21a, and a frame right side wall 2a.
It has a locking projection 21c fitted into the through hole formed in the above, and a locking portion 21e forming a gap 21d into which the locking projection 2s formed at the upper end of the right side wall 2a is fitted. Then, by fitting the locking protrusion 2s into the gap 21d, the locking portion 21e is locked to the locking protrusion 2s, and
By engaging and locking the locking protrusion 21c in the locking hole 2r of the right side wall 2a, the lock gear second cover 21 is moved to the right side wall 2a.
It is detachably attached so as to cover the deceleration sensing means 7.

As shown in FIG. 24, the deceleration sensing means 7
Is a case 7a, a lever 7b swingably supported by the case 7a, and a case 7a that is housed in the case 7a and is normally in a state indicated by a solid line. Two points are set when the vehicle decelerates more than a predetermined amount. The inertial body 7c swinging at the position of the chain line is provided.

As shown in FIG. 25, the case 7a is formed in the shape of a container having a rectangular cross section, and the inertial member 7 is formed at the bottom thereof.
The mounting portion 7d of c is formed. Further, engaging projections 7g and 7h having trapezoidal cross sections are formed on the front wall 7e and the rear wall 7f of the case 7a, respectively. That is, the side walls 7g ₁ , 7g ₂ , 7h ₁ , 7h ₂ of the engaging protrusions 7g, 7h are the side walls 13 of the concave fitting portions 13j, 13k of the guide members 13h, 13i.
It is an inclined surface having the same inclination angle as j ₁ , 13j ₂ , 13k ₁ , 13k ₂ . As is clear from FIG. 9A, one end portion of the engaging projection 7g in the longitudinal direction is an inclined surface 7g ₃ .
Although not shown, one end portion of the other engaging projection 7h in the longitudinal direction is also an inclined surface. These engaging ridges 7
g and 7h are adapted to be fitted into the concave fitting portions 13j and 13k of the guide members 13h and 13i in the lock gear first cover 13. The lever 7b has a rear end rotatably supported by the case 7a, and a front end of the lever 7b has a locking claw 7i engageable with the teeth 14c of the lock gear 14.
Is provided.

As shown in FIG. 26, the inertial body 7c has a hollow cylindrical small mass portion 7j formed in the lower portion thereof, and a frustoconical solid cone having a larger diameter than the small mass portion 7j. A trapezoidal large mass portion 7k is formed. The inclination angle of the outer peripheral side surface of the large mass portion 7k is set to a size that substantially coincides with the inner surface of the front wall 7e when the inertial body 7c swings to the maximum as described later. Further, a conical operating protrusion 7m is formed on the large mass portion 7k. In this way, by making the upper portion of the inertial body 7c have a larger mass than the lower portion, the deceleration of the inertial body 7c can be sensed more sensitively.

As shown in FIG. 24, the inertial member 7c constructed in this manner has the placing portion 7d of the case 7a as described above.
Placed on. The inertial body 7c mounted on the mounting portion 7d is
In a normal state, as shown by a solid line, the standing portion stands upright with respect to the mounting portion 7d, and the upper end of the operating protrusion 7m on the upper portion of the lever 7
It is fitted in a truncated conical recess 7n formed in b. In this normal state, the lever 7b is held in a substantially horizontal position shown by the solid line, and at this solid line position of the lever 7b, the lever 7b is in the disengaged position where the locking claw does not engage with the tooth 14c of the lock gear 14. ..

When a deceleration of a predetermined magnitude acts on the vehicle, the inertial body 7c tilts until the outer peripheral surface of the large mass portion 7k substantially contacts the inner surface of the front wall 7e, as shown by the chain double-dashed line. Due to the inclination of the inertial body 7c, the operating projection 7m pushes the lever 7b upward, so that the lever 7b rotates to the position indicated by the chain double-dashed line. At this two-dot chain line position of the lever 7b,
The lever 7b is in the engagement position where the locking claw engages with the teeth of the lock gear 14.

By the way, the inertial body 7c is provided with an operating protrusion 7m.
With a small inclination of c, the turning stroke of the lever 7b increases. As a result, the arm length of the lever 7b can be shortened,
The deceleration sensing means 7 can be made compact.

The deceleration sensing means 7 configured as described above
As shown in FIG. 24, the engaging protrusions 7g and 7h
The concave fitting portions 13j of the guide members 13h and 13i at 3g,
It is accommodated in the accommodating portion 13g by fitting 13k in the longitudinal direction. In this case, since one end of each of the engaging protrusions 7g and 7h is an inclined surface as described above, the engaging protrusions 7g and 7h can be smoothly fitted into the concave fitting portions 13j and 13k. it can. Also, both engaging ridges 7g, 7
Upper and lower side walls 7g ₁ , 7g ₂ , 7h ₁ , 7 at the projecting end of h
The length a between h ₂ is the engaging protrusion 7g of the concave fitting portions 13j, 13k,
It is set to be larger than the distance b between the upper and lower side walls 13j ₁ , 13j ₂ , 13k ₁ , 13k ₂ at the position corresponding to the protruding end position of 7h. The engaging protrusions 7g and 7h are concave fitting portions 13.
When fitted in j and 13k, the case 7a is relatively firmly supported by the guide members 13h and 13i by the elastic force of the elastic deformation of the housing portion 13g and the case 7a. In particular, the engaging protrusions 7g and 7h and the concave fitting portion 13
Since the side walls of j and 13k are both inclined surfaces, a wedge effect can be obtained between the guide members 13h and 13i and the engaging protrusions 7g and 7h, and the case 7a is formed by the guide member 1a.
It is more firmly supported by 3h and 13i.

As shown in FIG. 27, the webbing guide 2
2 is arranged between both side walls 2a and 2b of the frame 2,
Main body 2 having a hole 22f through which the webbing 3 penetrates in the center
2a, projecting shafts 22b and 22c projecting from both ends of the main body 22a in the longitudinal direction and slidably fitted in the guide holes 2p and 2q of the side walls 2a and 2b, and similarly from both ends of the main body 22a. Flange portions 22d and 22e, which are respectively provided so as to project in the longitudinal direction and contact the upper end surfaces of both side walls 2a and 2b.
It consists of and.

The webbing guide 22 is provided on both side walls 2a according to the winding amount of the webbing 3 of the reel shaft 4.
The webbing 3 slides along the guide holes 2p and 2q of 2b to smoothly wind up and pull out the webbing 3 and protect the webbing 3.

Next, the operation of the main pawl 17 and the backup pawl 20 will be described in detail with reference to FIGS. 28 and 29. 28 and 29, the upper I describes the operation of the main pawl 17, and the lower II describes the operation of the backup pawl 20. Further, FIGS. 28 and 29 are schematic representations,
On the main pawl 17 side, the teeth 2f, the locking claw 17d, and the three cam holes 14k, 14m, and 14n are shown on the same plane, and both the main pawl 17 side and the backup pawl 20 side are on the right side in FIG. The state as seen is described.

In FIG. 28, the pawl spring 18
(Not shown in FIG. 28; see FIG. 1, etc.)
The reel shaft 4 (only the through hole 4m through which the main body 19a of the joint pin 19 penetrates and the main pawl 17 provided on this reel shaft 4 are shown in FIG. 28) is connected to the lock gear 14 (similarly to the cam holes 14k and 14m in FIG. 28). , 1
4n), the reel shaft 4 rotates relative to the lock gear 14 in the β direction until the main body 19a comes into contact with the upper end edge of the cam hole 14k. The normal state shown in FIG.

In this normal state, the cam follower 19c of the joint pin 19 abuts on the upper edge of the cam hole 14m, and the cam follower 17f of the main pawl 17 abuts on the upper edge of the cam hole 14n. Then, the locking pawl 17d of the main pawl 17 is largely separated from the tooth 2f of the right side wall 2a, and the main pawl 17 is in the non-engaging position where the locking pawl 17d does not engage with the tooth 2f. On the other hand, cam followers 19c, 1
According to the rotation angle of the joint pin 19 which is determined by the respective contact positions of the 7f cam holes 14m and 14n with respect to the upper edge thereof, the backup pawl 20 becomes the position shown in FIG. That is, the locking pawl 20d of the backup pawl 20 is largely separated from the tooth 2g of the left side wall 2b, and the backup pawl 20 is also in the non-engaging position where the locking pawl 20d does not engage with the tooth 2g.

The reel shaft 4 has its first rotating shaft 4d.
(Not shown in FIG. 28: see FIG. 9) is rotated relative to the lock gear 14 in the α direction, that is, the main body 19
The through hole 4m through which a passes through is the first to third cam holes 14k, 14m of the lock gear 14 centering around the first rotating shaft 4d.
When rotated relative to 14n in the α direction, the boss portion 1 of the main body 19a and the main pawl 17 is rotated as shown in FIG.
7b slightly moves downward relative to the first cam hole 14k along the first cam hole 14k.

At the same time, the cam follower 17f is guided by the third cam hole 14n and moves slightly downward. In that case, due to the cam shape of the first cam hole 14k, the boss portion 17b also moves slightly to the left in the drawing, and the third cam hole 14n
The cam follower 17f moves slightly to the left due to the cam shape, but since the amount of leftward movement of the cam follower 17f is slightly larger than the amount of leftward movement of the boss 17b, the main pawl 17 moves in the β direction. It turns slightly to. As a result, the locking claw 17d approaches the tooth 2f.

At the same time, the cam follower 19c is guided by the second cam hole 14m and moves downward. In that case, due to the cam shape of the second cam hole 14m, the cam follower 19c
Also moves to the right, so that the arm 19b slightly rotates in the α direction around the main body 19a. By rotating the arm 19b in the α direction, the main body 19a also slightly rotates in the α direction, but since the reel shaft 4 rotates in the α direction, the main body 19a is rotated.
And the arm 19b hardly rotates relative to the reel shaft 4. Therefore, the backup pawl 20 is held at the non-engagement position as shown in FIG.

As shown in FIG. 7C, when the reel shaft 4 is further rotated relative to the lock gear 14 in the α direction, the main body 19a and the boss portion 17b are further lowered along the first cam hole 14k. Move to the left. At the same time, the cam follower 17f is guided by the third cam hole 14n and further moves slightly downward. Since the further leftward movement amount of the cam follower 17f is slightly larger than the further leftward movement amount of the boss portion 17b, the main pawl 17 further rotates slightly in the β direction, and the locking claw 17d causes the teeth 2f. Begin to engage.

At the same time, the cam follower 19c is guided by the second cam hole 14m and further moves downward and slightly to the left. In that case, due to the cam shape of the second cam hole 14m,
Since the cam follower 19c also moves slightly downward and to the left, the arm 19b hardly rotates. However, since the reel shaft 4 is further rotated in the α direction, the main body 19a
And the arm 19b rotates relative to the reel shaft 4 in the β direction. As a result, the backup pawl 20 slightly rotates relative to the reel shaft 4 in the β direction, and the locking claw 20d approaches the tooth 2g.

As shown in FIG. 9D, when the reel shaft 4 further rotates relative to the lock gear 14 in the α direction, the main pawl 17 similarly rotates a little more in the β direction with respect to the reel shaft 4. The locking claw 17d moves to the tooth 2f.
Will be engaged greatly. Similarly, the backup pawl 20 further rotates slightly in the β direction, and the locking pawl 20d
Begin to engage tooth 2g. In this way, the engagement of the locking claw 20d of the backup pawl 20 with the tooth 2g starts slightly later than the engagement of the locking claw 17d of the main pawl 17 with the tooth 2f.

When the reel shaft 4 further rotates relative to the lock gear 14 in the α direction as shown in FIG. 7 (e), the main pawl 17 and the backup pawl 20 are similarly moved with respect to the reel shaft 4, respectively. Further rotation in the β direction increases the engagement amount of the locking claw 17d with the tooth 2f and the engagement amount of the locking claw 20d with the tooth 2g. As shown in FIG.
By further relative rotation in the direction, the locking claw 17d is moved to the tooth 2f.
To be engaged with the teeth 2g of the locking claw 20d.
The amount of engagement with is further increased.

As shown in FIG. 9 (g), the further relative rotation of the reel shaft 4 in the α direction brings the locking claw 17d into complete engagement with the tooth 2f, so that the main pawl 17 is on the right side. Fully engage the teeth 2f of the wall 2a. On the other hand, the locking claw 20d is substantially engaged with the tooth 2f. As shown in FIG. 6H, the further relative rotation of the reel shaft 4 in the α direction maintains the complete engagement state with the teeth 2f of the locking claw 17d, and the backup pawl 2
0 fully engages the tooth 2g of the left side wall 2b.

As described above, in this embodiment, when the reel shaft 4 rotates relative to the lock gear 14 in the α direction, the locking pawl 17d of the main pawl 17 first engages with the tooth 2f of the right side wall 2a. After the start of the engagement, the locking claw 20d of the backup pawl 20 starts to engage with the tooth 2g of the left side wall 2b with a delay, and the locking claw 17d completes the engagement with the tooth 2f. The engagement with 2g is completed.
As a result, the engagement between the main pawl 17 and the teeth 2f and the engagement between the backup pawl 20 and the teeth 2g are prevented from occurring, and the engagement is ensured. Become.

Next, the operation of the retractor of the present embodiment thus constructed will be described. [Normal state in which deceleration above a predetermined value does not act on the vehicle] In this state, the inertial body 7c of the deceleration sensing means 7 does not tilt forward, so the lever 7b is at the solid line position shown in FIG. 7i is in a disengaged position away from the teeth 14c of the lock gear 14. Similarly, the locking claw 1 of the inertial body 15 is also provided.
5c, main pawl 17 and backup pawl 20
Are also in the disengaged position as shown in FIGS. 4 and 6, respectively.

Therefore, in this state, the seat belt retractor 1 is mainly operated by the biasing force applying means 5. That is, the reel shaft 4 is biased in the webbing winding direction β by the spring force of the power spring 8 of the biasing force imparting means 5, and the webbing 3 is wound up.

(State where seat belt is not worn) In this state, the tongue (not shown) attached to the webbing 3 and the buckle member (not shown) are separated from each other. Therefore, as described above, the webbing 3 is wound by the spring force of the power spring 8.

(State when pulling out the webbing) When the occupant pulls out the webbing 3 at a normal speed in order to mount the webbing 3, the reel shaft 4,
The lock gear 14 and the bush 9 rotate in the webbing pull-out direction α. Therefore, the power spring 8 is tightened. Further, since the inertial body 15 also rotates around the first rotation shaft 4d due to the rotation of the lock gear 14, a centrifugal force acts on the inertial body 15. However, since the moment about the axis 14f due to this centrifugal force does not act on the inertial body 15, the inertial body 15 does not rotate about the axis 14f during the rotation of the reel shaft 4 and is moved to the solid line position in FIG. It remains held. Therefore, the locking claw 15c
Does not engage the teeth 13c, the reel shaft 4 rotates smoothly, and the webbing 3 can be easily pulled out.

(The state when the tongue and the buckle member are joined together and the hand is released from the webbing) At the time when the occupant joins the tongue and the buckle member, the webbing 3 is longer than the pull-out length in the normal wearing state. Since the occupant is pulled out excessively, when the occupant releases the webbing 3 after the coupling operation, the webbing 3 is wound by the spring force of the power spring 8 until it fits the occupant's body.
At this time, the spring force of the power spring 8 is appropriately determined so that the webbing 3 does not give the occupant a feeling of pressure. At this time, the reel shaft 4 rotates, but the inertial body 15 remains held in the disengaged position. Then, while the vehicle is traveling, the seat belt retractor 1 maintains this state unless a deceleration of a predetermined value or more acts on the vehicle.

[State when deceleration exceeding a predetermined value acts on the vehicle] When the vehicle decelerates above a predetermined value due to sudden braking or the like while the vehicle is running, the seat belt lock operating means 6 and the deceleration detecting means 7 Work together. First, as the first step, the inertial body 7c of the deceleration sensing means 7 moves forward (the position shown by the chain double-dashed line in FIG. 4) by inertia, so that the lever 7b rotates upward and the chain double-dashed line in FIG. The position is indicated by. Therefore, the locking claw 7i of the lever 7b is in the engagement position where it engages with the tooth 14c of the lock gear 14. On the other hand, the webbing 3 is pulled out because the occupant tries to move forward due to the deceleration of the vehicle or more, and the reel shaft 4 and the lock gear 14 are both rotated in the pulling-out direction α by the pulling-out of the webbing 3. try to.

However, since the teeth 14c of the lock gear 14 immediately engage with the locking claw 7e, the lock gear 14 immediately stops rotating in the pull-out direction α. As a result, only the reel shaft 4 continues to rotate in the pull-out direction α, so that the reel shaft 4 rotates relative to the lock gear 14 in the α direction.

As a result of the relative rotation of the reel shaft 4 in the α direction, the main pawl 17 relatively rotates in the β direction with respect to the reel shaft 4 as shown in FIGS. The backup pawl 20 relatively rotates in the β direction with respect to the reel shaft 4 and engages with the tooth 2g with a slight delay thereafter. As a result, the reel shaft 4 is prevented from rotating in the webbing pull-out direction α. As a result, the withdrawal of the webbing 3 caused by the occupant attempting to move forward due to inertia is reliably prevented. This ensures that the occupant is restrained and protected.

[State when webbing is suddenly pulled out] In this state, the webbing 3 is suddenly pulled out, so that the reel shaft 4, the lock gear 14, and the inertial body 15 are rapidly moved in the webbing withdrawing direction α. Try to turn. However, since the spring force of the control spring 16 is not so large, the control spring 1
6 contracts, and the inertial body 15 causes inertial lag with respect to the lock gear 14. That is, the inertial body 15 not only revolves in the webbing pull-out direction α together with the lock gear 14, but also the shaft 14f relatively in the β direction with respect to the lock gear 14.
Rotate around.

Due to the rotation of the inertial body 15, the locking claw 15c moves to the engaging position where it abuts against the second stopper 14i as shown by the chain double-dashed line in FIG.
Engages with the tooth 13c. In that case, since the webbing sensor has good stability, the inertial body 15 reliably detects the sudden pulling out of the webbing 3 and engages the locking claw 15c with the tooth 13c.

The engagement of the locking claws 15c with the teeth 13c prevents the inertial body 15 from revolving and the lock gear 14 from rotating in the webbing pull-out direction α. Therefore, only the reel shaft 4 rotates in the webbing pull-out direction α. As a result, as described above, the reel shaft 4 rotates relative to the lock gear 14 in the β direction.

By the relative rotation of the reel shaft 4 in the α direction, the main pawl 17 rotates to engage with the tooth 2f, and the backup pawl 20 engages with the tooth 2f with a delay after that. As a result, the reel shaft 4 is prevented from rotating in the webbing pull-out direction α.
As a result, the withdrawal of the webbing 3 caused by the occupant attempting to move forward due to inertia is reliably prevented. This ensures that the occupant is restrained and protected.

The present invention is not limited to the above-mentioned embodiments, and various design changes can be made. For example, in the above-described embodiment, the flange-shaped portions 4 at both ends of the reel shaft 4
The case where the present invention is applied to the seat belt retractor of the type in which the main pawl 17 and the backup pawl 20 respectively provided on b and 4c are engaged with the teeth formed on the frame has been described, but the present invention is not limited to this. It can be applied to any type of seat belt retractor.

[0091]

As is apparent from the above description, according to the seat belt retractor of the first aspect of the present invention, even when the locking means actuating member is rotated during the normal webbing withdrawal or winding, It is possible to reliably prevent the inertial body from rotating carelessly about its rotation axis. Therefore,
The stability of the webbing sensor is improved.

According to the second aspect of the invention, since mechanical friction can be reduced, the stability of the webbing sensor is improved. Particularly in this case, since the inertial body does not rotate carelessly when the locking means operating member rotates normally, the locking claw may engage with the engaged portion of the frame and the rotation of the reel shaft may be stopped. It can be surely prevented. Therefore, the stability of the webbing sensor can be further improved.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a seat belt retractor according to the present invention in an exploded perspective view, and a central portion thereof.

FIG. 2 is an exploded perspective view showing an embodiment of a seat belt retractor according to the present invention in an exploded perspective view, and a left side portion thereof.

FIG. 3 is an exploded perspective view showing an embodiment of a seat belt retractor according to the present invention in an exploded perspective view and showing a right side portion thereof.

FIG. 4 is a left side view of the seat belt retractor with the cover removed showing an assembled state of the seat belt retractor of this embodiment.

5 is a sectional view taken along the line VV in FIG. 4 showing an assembled state of the seat belt retractor of this embodiment.

FIG. 6 is a partial sectional view taken along line VI-VI in FIG. 5, showing an assembled state of the seat belt retractor of this embodiment.

FIG. 7 is a right side view of a frame used in this embodiment.

FIG. 8 is a left side view of a frame used in this embodiment.

FIG. 9 is a front view of a reel shaft used in this embodiment.

FIG. 10 is a right side view of the reel shaft used in this embodiment.

FIG. 11 is a left side view of the reel shaft used in this embodiment.

FIG. 12 is a left side view of the bush used in this embodiment.

FIG. 13 shows a spring case used in this embodiment, (a) is a right side view thereof, and (b) is a sectional view taken along line XIII-XIII.

FIG. 14 shows the cover used in this example,
(A) is a left side view thereof, and (b) is a sectional view taken along line XIV-XIV.

FIG. 15 is a view showing a spring pin used in this embodiment.

FIG. 16 is a left side view showing a lock gear first cover used in this embodiment.

FIG. 17 is a right side view showing a lock gear first cover used in this embodiment.

FIG. 18 shows a lock gear used in this embodiment,
(A) is a right side view thereof, (b) is XVIIIB in (a)
-Cross-sectional view taken along line XVIIIB, (c) is XVII in (a)
It is a sectional view taken along the line IC-XVIIIC.

FIG. 19 shows the inertial body used in this example,
(A) is the left side view, (b) is the XIXB in (a)
It is sectional drawing which follows the XIXB line.

FIG. 20 shows a main pawl used in this embodiment, (a) is a left side view thereof, (b) is a front view thereof,
(C) is the right view.

FIG. 21 shows a joint pin used in this embodiment, (a) is its front view, (b) is XXIB in (a).
A cross-sectional view taken along the line -XXIB, (c) is a left side view thereof.

FIG. 22 shows a backup pawl used in this embodiment, (a) is a left side view thereof, (b) is a front view thereof,
(C) is the right view.

23A and 23B show a lock gear second cover used in this embodiment, where FIG. 23A is a left side view thereof, and FIG. 23B is a view seen from the direction XXIIIB in FIG.

FIG. 24 is a partially cutaway view of the deceleration sensing means used in this embodiment.

25A and 25B show a case, a lever and a locking claw of the deceleration sensing means, FIG. 25A is a front view thereof, and FIG. 25B is a right side view partially cut away.

FIG. 26 shows an inertial body of this deceleration sensing means, (a)
Is a plan view, (b) is a partially cutaway front view, and (c) is a bottom view thereof.

FIG. 27 shows a webbing guide used in this embodiment, (a) is a plan view thereof, (b) is a left side view thereof,
(C) is a sectional view taken along line XXVII-XXVII in (a).

FIG. 28 is an explanatory diagram for explaining a part of the operation of the main pawl and the backup pawl in this embodiment.

FIG. 29 is an explanatory diagram illustrating another part of the operation of the main pawl and the backup pawl in this embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Seat belt retractor, 2 ... Frame, 2a ... Right side wall, 2b ... Left side wall, 2f, 2g ... Tooth, 3 ... Webbing, 4 ... Reel shaft, 4d ... 1st rotating shaft, 5 ... Biasing force application means, 6 ... seat belt lock operating means, 7 ... deceleration sensing means, 8 ... power spring, 9 ... bush,
10 ... Spring case, 11 ... Cover, 12 ... Spring pin, 13 ... Lock gear first cover, 13c ... Teeth,
14 ... Lock gear, 14f ... Rotation shaft of inertial body, 14j ...
Rotating shaft of lock gear, 15 ... Inertia, 15c ... Locking claw,
16 ... Control spring, 17 ... Main pawl, 18 ...
Pawl spring, 19 ... Joint pin, 20 ... Backup pawl, 21 ... Lock gear second cover, G ... Center of gravity of inertial body, γ ... Straight line connecting rotation axis of lock gear and rotation axis of inertial body

Claims (2)

[Claims] 1. A reel shaft for winding webbing,
A frame that rotatably supports both ends of the reel shaft, and a frame that is disposed between the frame and the reel shaft to allow the reel shaft to rotate during normal operation and operate when necessary to rotate the reel shaft in at least the webbing pull-out direction. Lock means for preventing movement, deceleration sensing means for actuating when a deceleration of a predetermined value or more is applied to the vehicle, and lock actuating means for actuating the locking means by actuation of the deceleration sensing means, Further, the lock operating means normally rotates together with the reel shaft and operates relative to the reel shaft by the operation of the deceleration sensing means to operate the lock means, and a webbing. Has a webbing withdrawal speed sensing means that is activated when the withdrawal speed is more than a predetermined value, and Ebingu withdrawal rate sensing means,
The locking means operating member is rotatably provided between a non-operating position where the locking means operating member is free to rotate and an operating position where the locking means operating member is prevented from rotating at least in the webbing pull-out direction. In the seat belt retractor having an inertial body, the inertial body is a linear inertial line whose center of gravity connects the rotation axis of the inertial body and the rotation axis of the locking means operating member when the inertial body is in the non-operating position. A seat belt retractor, which is set so as to be positioned on an extension line of a body on a rotation axis side. 2. When the inertial body is in the operating position,
The seat belt retractor according to claim 1, wherein a locking claw that engages with an engaged portion provided on the frame is integrally provided on the inertial body.